I've run into a unique problem where right after installation of your forum, I move the automatically created "Forums" page to be a sub-page of another. I created a Category, Forum, and posted in that forum from the admin area.
When I go to view my forum page, it shows nothing. I checked the database for postmeta and it had 'wpbb-template.php' set for '_wp_page_template' meta-key for the post number that was created, as expected.
I've tried re-installing the forum twice now. Once I just left the automatically generated page where it was originally created and just added my category, forum, and post. It still didn't show up.